Multi-zone ec windows

ABSTRACT

Thin-film devices, for example, multi-zone electrochromic windows, and methods of manufacturing are described. In certain cases, a multi-zone electrochromic window comprises a monolithic EC device on a transparent substrate and two or more tinting zones, wherein the tinting zones are configured for independent operation.

INCORPORATION BY REFERENCE

An Application Data Sheet is filed concurrently with this specificationas part of the present application. Each application that the presentapplication claims benefit of or priority to as identified in theconcurrently filed Application Data Sheet is incorporated by referenceherein in its entirety and for all purposes.

FIELD

Embodiments disclosed herein relate generally to optical devices, andmore particularly to methods of fabricating optical devices andparticularly to electrochromic (EC) windows having multiple tintingzones.

BACKGROUND

Electrochromism is a phenomenon in which a material exhibits areversible electrochemically-mediated change in an optical property whenplaced in a different electronic state, typically by being subjected toa voltage change. The optical property is typically one or more of tint,transmittance, absorbance, and reflectance. For example, one well knownelectrochromic material is tungsten oxide (WO₃). Tungsten oxide is acathodically tinting electrochromic material in which a tintingtransition, bleached (untinted) to blue, occurs by electrochemicalreduction. When electrochemical oxidation takes place, tungsten oxidetransitions from blue to a bleached state.

Electrochromic materials may be incorporated into, for example, windowsfor home, commercial and other uses. The tint, transmittance,absorbance, and/or reflectance of such windows may be changed byinducing a change in the electrochromic material, that is,electrochromic windows are windows that can be darkened and lightenedreversibly via application of an electric charge. A small voltageapplied to an electrochromic device of the window will cause it todarken; reversing the voltage causes it to lighten. This capabilityallows control of the amount of light that passes through the windows,and presents an opportunity for electrochromic windows to be used asenergy-saving devices.

While electrochromism was discovered in the 1960s, electrochromicdevices, and particularly electrochromic windows, still unfortunatelysuffer various problems and have not begun to realize their fullcommercial potential despite much recent advancement in electrochromictechnology, apparatus, and related methods of making and/or usingelectrochromic devices.

SUMMARY

Thin-film devices, for example, electrochromic devices for windows, andmethods of manufacturing are described. Embodiments includeelectrochromic window lites having two or more tinting (or coloration)zones, where there is only a single monolithic electrochromic device onthe lite. The tinting zones are defined by virtue of the means forapplying potential to the device and/or by a resistive zone betweenadjacent tinting zones. For example, sets of bus bars are configured toapply potential across separate zones (areas) of the device and therebytint them selectively. The advantages include no visible scribe lines inthe viewable area of the EC window due to cutting through the EC deviceto make separate devices that serve as tinting zones.

One embodiment is an electrochromic window lite including a monolithicEC device on a transparent substrate, the monolithic EC device includingtwo or more tinting zones, each of said two or more tinting zonesconfigured for operation independent of the others and each having itsown associated bus bars, where the two or more tinting zones are notseparated from each other by isolation scribes. That is, the EC devicestack is not cut through, but rather is intact as a monolithic device.For example, there may be two tinting zones on the lite and theassociated bus bars arranged are located at opposing edges of the lite(e.g., vertically oriented), wherein a set of bus bars is associatedwith each of the two tinting zones.

Bus bars may be configured to enhance coloring of tinting zones. Incertain embodiments, bus bars have varying width along their length; thevarying width of the bus bars may enhance the tinting front and/orpromote selective tinting in a particular tinting zone via voltagegradients. In other embodiments, bus bars may be composites, having bothhigh electrically conductive regions and resistive regions, configuredto enhance tinting fronts and/or promote selective tinting in aparticular tinting zone via voltage gradients. One embodiment isdirected to an electrochromic window lite comprising a monolithic ECdevice on a transparent substrate and at least one pair of lengthwisevariable bus bars configured to produce a tint gradient zone on themonolithic EC device when energized.

In certain embodiments, the two or more tinting zones are separated by aresistive zone which inhibits, at least partially, the flow ofelectrons, ions or both across the resistive zone. Resistive zones may,e.g., be parallel to bus bars and/or orthogonal to bus bars.

Resistive zones may include modification of the EC device and/or one orboth transparent conductor layers (TCOs) of the EC device. Monolithic EClites having two or more tinting zones may be integrated into insulatingglass units (IGUs). The mate lite may or may not also be anelectrochromic lite, and may or may not also have tinting zones.

One embodiment is directed to an electrochromic window lite comprising amonolithic EC device disposed on a transparent substrate and a resistivezone. The monolithic EC device is comprised of first and secondtransparent conductor layers and an EC stack between the first andsecond transparent conductor layers. The resistive zone in one of thefirst and second transparent conducting layers. The resistive zone has ahigher electrical resistance than a portion of the one of the first andsecond transparent conducting layers outside the resistive zone. In onecase, the resistive zone is a linear region in the one of the first andsecond transparent conducting layer with thinner or absent material.

Certain aspects of the disclosure pertain to an electrochromic windowlite that may be characterized by the following features: a monolithicEC device on a transparent substrate, the monolithic EC devicecomprising: two or more tinting zones, each of the two or more tintingzones configured for operation independent of the others and having itsown associated bus bars. In certain embodiments, the two or more tintingzones contain only a partial cut through the uppermost TCO of themonolithic EC device to form a resistive zone between each of said twoor more tinting zones.

In certain embodiments, the associated bus bars located at opposingedges for each of the two tinting zones. In certain embodiments, theelectrochromic window lite is incorporated into an insulated glass unit,which may have a mate lite that is (i) not an electrochromic lite or(ii) a monolithic electrochromic lite with a single tinting zone, or(iii) a monolithic electrochromic lite with two or more tinting zones(where the tinting zones of the mate lite may be aligned with those ofthe electrochromic window lite), or (iv) an electrochromic lite withthree or more tinting zones. In such embodiments, the electrochromicwindow lite may be configured to tint in one or more tinting zones to<1% T.

In some implementations, the resistive zone substantially spans acrossthe monolithic EC device. In some implementations, the resistive zone isbetween about 1 nm wide and about 10 nm wide. In certain embodiments,the resistive zone is formed by removing between about 10% and about 90%of the uppermost TCO material along the resistive zone. As an example,the resistive zone may be formed by laser irradiation of the uppermostTCO. As a further example, each of the two or more tinting zonesassociated bus bars are formed by laser irradiation during formation ofthe resistive zone by cutting through a single bus bar.

Other aspects of the disclosure pertain to methods of forming amonolithic EC device comprising two tinting zones, where the methods maybe characterized by the following operations: (a) forming the monolithicEC device; (b) applying a single bus bar to the top

TCO of the monolithic EC device; (c) cutting through the single bus baralong its width; and, (d) cutting at least part way through the top TCO,but not through the electrode layer adjacent to the top TCO, to form aresistive zone between the two tinting zones. In certain embodiments,operation (c) forms separate bus bars for each of the two tinting zonesfrom the single bus bar. In some implementations, operations (c) and (d)are performed in a single cutting step.

In some implementations, the resistive zone substantially spans thewidth of the monolithic EC device. In certain embodiments, the resistivezone is between about 1 nm wide and about 10 nm wide. In certainembodiments, the resistive zone is formed by removing between about 10%and about 90% of the uppermost TCO material along the resistive zone. Asan example, the resistive zone may be formed by laser irradiation of theuppermost TCO.

Another aspect of the disclosure concerns electrochromic window litescharacterized by the following features: an EC device on a transparentsubstrate, the EC device comprising bus bars; a region of thetransparent substrate that is not covered by the EC device, where theregion capable of providing, when not mitigated, a bright spot or brightregion when the EC device is tinted; and an obscuring material over theregion, wherein the material has a lower transmittance than thesubstrate. In some embodiments, the region is a pinhole, a scribe line,or an edge line.

Yet another aspect of the disclosure concerns methods of obscuring apotentially bright area produced by a region of a transparent substratethat is not covered by an EC device. Such methods may be characterizedby the following operations: (a) providing an electrochromic lite havingthe EC device on a substrate; (b) identifying a site of the potentiallybright area on the substrate; and (c) applying an obscuring material tothe site. The obscuring material has a lower transmittance than thesubstrate. In certain embodiments, the region is a pinhole, a scribeline, or an edge line.

These and other features and advantages will be described in furtherdetail below, with reference to the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description can be more fully understood whenconsidered in conjunction with the drawings in which:

FIG. 1 depicts fabrication of an IGU with an EC lite and associatedtinting schemes.

FIGS. 2A and 2B depict an IGU having an EC lite with two tinting zonesdelineated by laser scribe, and associated tinting schemes,respectively.

FIGS. 3A and 3B depict fabrication of an IGU with an EC lite havingtinting zones configured on a monolithic EC device and associatedtinting schemes, respectively.

FIG. 3C depicts various tinting schemes as a function of tinting frontof tinting zones.

FIGS. 3D and 3E depict fabrication of an IGU having two EC lites, whereeach of the EC lites has two tinting zones, and associated tintingschemes, respectively.

FIGS. 4A-C depict fabrication of an IGU with an EC lite and associatedtinting schemes, respectively.

FIGS. 4D-F depict EC lites, each having a gradient tinting zone.

FIGS. 5A and 5B depict fabrication of an IGU with an EC lite andassociated tinting schemes, respectively.

FIG. 5C depicts a perspective and a cross section of an EC device havingtwo tinting zones separated by a resistive zone.

FIG. 5D depicts a perspective and a cross section of an EC device havingtwo tinting zones by virtue of a resistive zone.

FIG. 5E shows graphs of V_(TCL) for two transparent conducting oxidelayers of an EC device configured with a resistive zone created byinhibiting the electrical conductivity of only one of the transparentconducting oxide layers.

FIG. 5F depicts a tinting pattern of the EC lite described in relationto FIG. 5C.

FIGS. 5G to 5K depict EC devices configured with a resistive zonecreated by inhibiting the electrical conductivity of only one of thetransparent conducting oxides.

FIG. 6A depicts a resistive zone establishing a closed perimeterdefining a separate tinting zone.

FIG. 6B depicts a resistive zone establishing an open perimeter defininga separate tinting zone.

DETAILED DESCRIPTION

Certain embodiments are directed to optical devices, that is, thin-filmdevices having at least one transparent conductor layer. In the simplestform, an optical device includes a substrate and one or more materiallayers sandwiched between two conductor layers, one of which istransparent. In one embodiment, an optical device includes a transparentsubstrate and two transparent conductor layers. Certain embodimentsdescribed herein, although not limited as such, work particularly wellwith solid state and inorganic electrochromic devices.

FIG. 1 depicts fabrication of an IGU, 120, with an EC lite, 100, whichincludes a monolithic EC device and associated pair of bus bars, 105,which energize the device each via a transparent conductor, the pair oftransparent conductors sandwich the EC materials between them so that apotential can be applied across the device materials. The IGU isfabricated by combining EC lite 100 with a spacer, 110, and a mate lite,115, along with the appropriate sealants and wiring (not shown) to thebus bars. As depicted on the bottom half of FIG. 1, the IGU can betransparent (left), tinted to an intermediate state (middle) or fullytinted (right). However, there is no possibility of tinting the viewablearea of the lite in different areas or “zones.” Conventional technologydoes exist to achieve this end, however.

FIG. 2A depicts an IGU, 220, having an EC lite, 200, with two tintingzones delineated by laser scribe, 225. Each tinting zone has anassociated pair of bus bars, 205 and 207, respectively. The EC lite 200may be incorporated into an IGU, 220, as described in relation toFIG. 1. Scribe line 225 cuts through both of the transparent conductorlayers which sandwich the electrochromic materials, along with the ECdevice layer(s), so that there effectively two EC devices, onecorresponding to each tinting zone, on the EC lite 200. Scribe line 225may not be visually discernible when the EC lite is not tinted, asdepicted in FIG. 2A, i.e. in the untinted state (bleached or neutralstate).

FIG. 2B depicts three possible tinting schemes of IGU 220. As shown, IGU220 may have the top zone tinted and the bottom zone untinted (left),the top zone untinted and the bottom zone tinted (middle) or both thetop and bottom zones tinted (right). Although such windows offerflexibility in tinting, when both zones are tinted, scribe line 225 isvisually discernible and is unattractive to an end user because there isa bright line across the middle of the viewable area of the window. Thisis because the EC material in the area has been destroyed and/ordeactivated from the scribe line that cut through the device. The brightline can be quite distracting; either when one is looking at the windowitself, or as in most cases, when the end user is trying to view thingsthrough the window. The bright line against a tinted background catchesone's eye immediately. Many approaches have been taken to create tintingzones in optical devices, but they all involve some sort of physicalsegmentation of a monolithic optical device into two or moreindividually operable devices. That is, the functionality of the ECdevice is destroyed along the scribe line, thus effectively creating twodevices from a monolithic single device. Certain embodiments describedherein avoid destroying the EC device function between adjacent tintingzones.

One approach to overcoming the visually distracting bright line createdby a laser scribe in the viewable area of an EC lite is to apply atinted material to the lite, e.g. on the scribe line or on an opposingside of the lite, in order to obscure or minimize the light passingthrough the scribe area. Thus, when tinting zones adjoining the scribeare tinted, the scribe line will be less discernible to the end user.When neither of the adjoining tinting zones is tinted, the tintedmaterial in the scribe line area will be almost or completelyindiscernible because it is a thin tinted line against a large untintedbackground, which is harder to see than a bright line against a tintedbackground. The thin tinted line need not be opaque, a limited amount ofabsorption of the visible spectrum can be used, e.g., absorption thatwill tone down the bright line created when the full spectrum emanatesthrough scribe line 225. Methods for obscuring pinhole defects inoptical devices are described in, for example, described in U.S.Provisional Patent Application Ser. No. 61/610,241, filed Mar. 13, 2012,and described in PCT Application Serial No. PCT/US2013/031098 filed onMar. 13, 2013, which are both hereby incorporated by reference in theirentirety. Whether obscuring pin holes, scribe lines, edge lines, or thelike, the methods obscure bright areas on EC devices, e.g. by applyingtinted material to such areas to make them harder to see to the enduser. Edge lines exist where a coating such as a monolithicelectrochromic coating, does not extend to the spacer of an IGU (e.g.,element 110 of FIG. 2A). In this region, a bright line or wider area isvisible when viewing the IGU directly. As understood by those of skillin the art, the obscuring methods described in the present applicationand in PCT/US2013/031098 have equal applicability to pin holes, edgelines, scribe lines, and the like. The methods described in theaforementioned patent application are particularly useful for obscuringscribe or edge lines in the visible area of an optical device such as anEC device. One embodiment is a method of obscuring a scribe line in theviewable area of an EC window, the method including applying a methodused to obscure pinholes as described in the aforementioned U.S./PCTPatent application. For example, one method includes applying a tintedmaterial to the scribe line and optionally the area adjacent the scribeline. In another example, the glass at the bottom of the scribe linetrench (and optionally some adjoining area) is altered so as to diffuselight that passes therethrough, thus ameliorating the “bright line”effect.

Tinting Zones

As discussed above, certain embodiments described herein avoiddestroying the EC device functionality between adjacent tinting zones.Though scribe lines may be visually obscured by application of tintedmaterials to the lite as described above, the inventors have found thatit may be often preferable to maintain the functional integrity of amonolithic EC device, rather than scribe it into discrete devices andthus conventional tinting zones. The inventors have discovered thattinting zones may be created by: 1) configuring the powering mechanism(e.g. bus bars, wiring thereto and associated powering algorithms) ofthe optical device appropriately, 2) configuring the EC device such thatadjacent tinting zones are separated by a resistive zone, or 3)combination of 1) and 2). For example, number 1) may be achieved byappropriately configuring one or more bus bars such that they can beactivated independently of other bus bars on the same monolithic ECdevice. Thus tinting zones are created without the need to physicallyseparate individual EC devices to create corresponding tinting zones. Inanother example, a resistive zone allows coloration and bleaching ofadjacent tinting zones on a single EC device without destroyingfunctionality in the resistive zone itself. A resistive zone can referto an area of the monolithic optical device, e.g. an EC device, wherethe function is impaired but not destroyed. Typically, the functionalityin the resistive zone is merely slowed relative to the rest of thedevice. Impairment might also include diminished capacity for ions inone or more of the layers of the EC device. For example, one or more ECdevice layers may be made denser and therefore be able to hold fewerions, and therefore color less intensely than the bulk device, but stillfunction. A resistive zone is achieved in at least one of the followingways: i) the electrical resistivity of one or both of the transparentconductor layers is impaired, ii) one or both of the transparentconductor layers is cut, without cutting through the optical devicestack therebetween, iii) the function of the optical device stack (notincluding the transparent conductor layers) is impaired, and iv)combinations of i)-iv). For example, a resistive zone may be createdwhere one or both of the transparent conductor layers is fabricatedthinner or absent, e.g. along a linear region, so as to increaseelectrical resistivity along the linear region of the resistive zone. Inanother example, one of the transparent conductor layers may be cutalong the width of the device, while the other transparent conductor isleft intact, either of uniform thickness or thinner, along the resistivezone. In yet another example, the function of the EC device may beinhibited along a line, so that it resists ion transport, while thetransparent conductor layers may or may not be altered along the sameline. Resistive zones are described in more detail below in terms ofspecific, but non-limiting examples. If the resistive zone is in one ofthe transparent layers, the other transparent layer may be left intact(e.g., uniform composition and thickness).

Configuring Powering Mechanism of EC Devices

One embodiment is an electrochromic window lite including a monolithicEC device on a transparent substrate, the monolithic EC device includingtwo or more tinting zones, each of the two or more tinting zonesconfigured for operation independent of the others and having its ownassociated bus bar or bus bars. In certain embodiments, the two or moretinting zones are not separated from each other by isolation scribes;that is, the EC device and associated transparent conductors do not haveisolation scribes that cut through any of these layers. For example,there may be two tinting zones on the EC lite and two pairs of bus bars,wherein each pair is associated with a tinting zone and both pairs arelocated at or near opposing edges of the EC lite e.g., the bus bars maybe vertically oriented at or near opposing vertical edges with a set ofbus bars for each of the two tinting zones. Such lites may be integratedinto insulating glass units (IGUs).

FIG. 3A depicts fabrication of an IGU, 300, with an EC lite, 305 havingtwo tinting zones (upper and lower tinting zones) configured on amonolithic EC device, i.e., there are no laser scribes or other physicalsectioning (e.g. bifurcation) of the monolithic EC device or transparentconductor layers on the lite. Each of bus bar pairs, 205 and 207, isconfigured to energize independently of each other. Thus, referring toFIG. 3B, IGU 300 has three tinting schemes besides the untinted state(bleached or neutral state) depicted in FIG. 3A. FIG. 3B shows thesethree tinting schemes where the top zone may be tinted while the bottomzone is not (left), the bottom zone may be tinted while the top zone isnot (middle), or both zones may be tinted (right). In contrast to an EClite having two distinct EC devices divided at a scribe line, eachtinting zone of lite 305, when tinted, has a “tinting front” 310. Atinting front can refer to an area of the EC device where the potentialapplied across the devices TCOs by the bus bars reaches a level that isinsufficient to tint the device (e.g. by movement of ions through thelayers of the device to balance charge). Thus, in the example depicted,the tinting front 310 corresponds roughly to where the charge isbleeding off into the area of the transparent conductor that is betweenthe pair of bus bars that are not energized.

The shape of a tinting front may depend upon the chargingcharacteristics of the transparent conductors, the configuration of thebus bars, wiring and powering thereto, and the like. The tinting frontmay be linear, curved (convex, concave, etc.), zigzag, irregular, etc.For example, FIG. 3B depicts the tinting front 310 as a linearphenomenon; that is, the tinting front 310 is depicted as located alonga straight line. As another example, FIG. 3C depicts various tintingschemes as a function of tinting front of each of the tinting zones, inthis case lower and upper tinting zones. In the illustrated example, thetinting front is curved (e.g., concave or convex) along the tintingfront. In certain embodiments, it may be desirable that when bothtinting zones are tinted, the tinting of the EC lite is total anduniform. Thus a convex tinting front may be desirable, so acomplimentary concave tinting front may be used in an adjacent zone, oranother convex tinting front may be used to ensure sufficient chargereaches the entire device for uniform tinting. In certain cases, thetinting front may not be a clean line as depicted in FIGS. 3B and 3C,but rather have a diffuse appearance along the tinting front due to thecharge bleeding off into the adjacent tinting zone which is not poweredat the time.

In certain embodiments, when the EC lite with tinting zones isincorporated into an IGU or a laminate for example, the mate lite mayalso be an EC lite, having tinting zones or not. Insulated glass unitconstructions having two or more (monolithic) EC lites are described inU.S. Pat. No. 8,270,059, which is hereby incorporated by reference inits entirety. Having two EC lites in a single IGU has advantagesincluding the ability to make a near opaque window (e.g. privacy glass),where the percent transmission (% T) of the IGU is <1%. Also, if the EClites are two-state (tinted or bleached) there may be certain tintingcombinations made possible, e.g. a four-tint-state window. If the EClites are capable of intermediate states, the tinting possibilities maybe virtually endless. One embodiment is an IGU having a first EC litehaving two or more tinting zones and a mate lite that is a monolithic EClite. In another embodiment, the mate lite also has two or more tintingzones. In this latter embodiment, the tinting zones may or may not bethe same in number or aligned with the tinting zones of the first EClite with which it is registered in the IGU. Exemplary constructsillustrating these descriptions follow.

FIG. 3D depicts fabrication of an IGU, 325, having two EC lites, 305 and320, where each of the EC lites has two tinting zones, each of thetinting zones created by appropriately configured bus bar pairs, 205 and207 at or near two opposing edges. In this illustrated example, thetinting zones of EC lites 305 and 320 are registered, that is, they arealigned with each other and of the same area, but this need not be theconfiguration. For example, the tinting fronts from opposing EC lites305 and 320 could overlap each other when tinted in another embodiment.FIG. 3D depicts IGU 325 in an untinted state (bleached or neutralstate). Also, each of the tinting zones is capable of only two states,tinted or bleached. Even so, this enables a wide range of tintingschemes for IGU 325. Besides the untinted state, IGU 325 is capable ofeight tint states. FIG. 3B depicts three of the possible tint states(i.e. where one EC lite of IGU 325 is tinted in one of the threeconfigurations shown in FIG. 3B). FIG. 3E depicts the other fivepossible tint states for IGU 325. If the top tinting zones of both EClites are tinted simultaneously, and the bottom two zones are not, thenthe top half of the IGU is very dark, while the bottom is untinted (topleft IGU). If both of the top tinting zones are not tinted, and thebottom two zones are tinted, then the bottom half of the IGU is verydark, while the top is untinted (top middle IGU). If all four zones ofthe EC lites are tinted, then the entire window is very dark (top rightIGU). For example, the combined tinting of all tinting zones in tworegistered EC lites can achieve <1% T. If one of the top zones in the EClites is tinted and both of the bottom zones are tinted, then the tintstate on the bottom left of FIG. 3E is created. Likewise, if one of thebottom zones is tinted and both of the top zones are tinted, then thetint state on the bottom right of FIG. 3E is created.

One embodiment is an IGU having two or more EC lites, wherein at leasttwo of the two or more EC lites includes multiple tinting zones asdescribed herein. One embodiment is an IGU having two or more EC lites,wherein a first of the two or more EC lites includes multiple tintingzones created by conventional isolation scribes, and a second of the twoor more EC lites includes tinting zones as described herein bytechniques other than isolation scribes.

Configurations such as those depicted in FIGS. 3B and 3E may beparticularly useful in applications such as creating day lighting zonesvs. occupant (glare) control zones. Day lighting transoms are verycommon. For example, creating “virtual transoms” with a piece of glassand thus removing the frame and associated glazier labor has a costbenefit as well as better sight lines. Also, having a variety of tintstates such as those depicted in Figures 3B and 3E allows forcustomization of room lighting based on the amount and location of thesun striking individual windows.

Certain embodiments pertain to methods of transitioning an EC litehaving two or more tinting zones. In one embodiment, an EC lite havingthree or more tinting zones is transitioned across the three or moretinted zones from a first zone at one edge of the device, to a secondadjacent tinting zone, and then to a third tinting zone, adjacent to thesecond zone. In other words, the tinting zones are used to give theeffect of drawing a physical shade across the window, without actuallyhaving a physical shade, since EC windows may eliminate the need forphysical shades. Such methods may be implemented with conventional zonedEC lites or those described herein. This is illustrated in FIGS. 4A-Cwith respect to an EC lite of an embodiment.

Referring to FIG. 4A, an EC lite, 400, is configured with a first set ofbus bars, 405, a second set of bus bars 407, and a third set of busbars, 409. The three sets of bus bars are configured so as to createthree tinting zones, respectively. Although EC lite 400 in FIG. 4A isincorporated into an IGU, 420, using a spacer 410 and a mate lite 415,lamination to a mate lite (EC lite or otherwise) or use as a single EClite is also possible.

Referring to FIG. 4B, assuming that each of the tinting zones is tintedas a two-state zone, then the three tinting zones may be activatedsequentially, e.g. from top to bottom as depicted, to create a curtaineffect, i.e. as if one were lowering a roller shade or drawing a Romanshade over the window. For example, the top zone may be fully tinted,then the second zone may be fully tinted, finally the third zone may befully tinted. The tinting zones could be sequentially tinted from thebottom up or in the middle and then the upper and lower zones tinted,depending upon the desired effect.

Another method is to tint the tinting zones as described with respect toFIG. 4B, except that before transition in a particular tinting zone iscomplete, transition in an adjacent tinting zone begins, which can alsocreate a curtaining effect. In the illustrated example of FIG. 4C, thetop tinting zone's tinting is initiated (top left), but before tintingis complete in the top zone, the middle zone's tinting is initiated.Once the top zone's tinting is complete, the middle zone's tinting isnot yet complete (top center). At some point during the transition ofthe middle zone, the bottom zone's tinting is initiated. Once the middlezone's tinting is complete, the bottom zone's tinting is not yetcomplete (top right), thus the top and middle zones are fully tinted andthe bottom zone's tinting is yet to be completed. Finally, the bottomzone is fully tinted. Using tinting zones with intermediate statecapability will increase the possible variations of tinting schemes.

Lengthwise Variable Busbars

In certain embodiments, an EC lite may be configured to have one or moretint gradient zones. In these embodiments, the EC lite has an EC device,such as, e.g., a monolithic EC device on a transparent substrate, andalso has at least one pair of bus bars with geometry and/or materialcomposition that varies along their lengths to vary electricalresistance lengthwise (lengthwise variable busbars). This variation inresistance can produce a lengthwise gradient in the voltage applied tothe EC device supplied across bus bars (V_(app)) and a lengthwisegradient in the local effective voltage (V_(eff)) in the EC device. Theterm V_(eff) refers to the potential between the positive and negativetransparent conducting layers at any particular location on the ECdevice. The lengthwise gradient of the V_(eff) may generate acorresponding tint gradient zone that varies lengthwise in a regionbetween the pair of bus bars when energized. In these embodiments, thelengthwise variable bus bars will have resistance profiles along theirlengths that are functions of both the local bus bar geometry andresistivity. In certain embodiments, the bus bars are designed so thatthe resistance is lowest at one end of the bus bar and highest at theother end of the bus bar. Other designs are possible, such as designswhere the resistance is lowest in the middle of a bus bar and highest atthe ends of the bus bar. A description of voltage profiles in various ECdevices powered by bus bars can be found in U.S. Patent application Ser.No. 13/682,618, titled “DRIVING THIN FILM SWITCHABLE OPTICAL DEVICES,”filed on Nov. 20, 2013, which is hereby incorporated by reference in itsentirety.

The local material composition of a bus bar may determine its localresistivity. It is contemplated that the bus bar material composition,and therefore the bus bar resistivity may vary along the length of thebus bar in certain embodiments. The resistivity can be tailored based onvarious compositional adjustments known to those of skill in the art.For example, resistivity can be adjusted by adjusting the concentrationof a conductive material in the bus bar composition. In someembodiments, bus bars are made from a conductive ink such as a silverink. By varying the concentration of silver in the ink along the lengthof the bus bar, one can produce a bus bar in which the resistivitylikewise varies along the length. The resistivity can also be varied byother compositional adjustments such as the local inclusion of resistivematerials in the bus bar or the variation of the composition of aconductive component to adjust its resistivity. Slight variations incomposition can change the resistivity of certain conductive materialssuch as conductive polymers. In certain embodiments, the electricalconductivity of the bus bar material is constant, but the thicknessand/or width of the bus bar varies along its length.

The value of the voltage that can be applied at any position on the busbar is a function of the location where the bus bar connects to anexternal power source and the resistance profile of the bus bar. A busbar may be connected to the source of electrical power at locationswhere the bus bar has least resistance, although this is not required.The value of the voltage will be greatest at the locations where thepower source connection attaches to the bus bars. The decrease involtage away from the connection is determined by the distance from theconnection and the resistance profile of the bus bars along the pathfrom the connection to the point where voltage is measured. Typically,the value of voltage in a bus bar will be greatest at the location wherean electrical connection to the power source attaches and least at thedistal point of the bus bar. In various embodiments, a bus bar will havelower electrical resistance at an end proximal to the connection to theelectrical source and a higher resistance at a distal end (i.e. theresistance is higher at the distal end than at the proximal end).

Each of the lengthwise variable bus bars may have linearly, stepped, orotherwise varying geometry and/or material composition along its length.For example, a bus bar with lengthwise-varying geometry may have itswidth, height, and/or other cross-sectional dimension linearly taperingfrom the proximal end to the distal end. As another example, a bus barmay be comprised of multiple segments with stepwise decreasing widths orother dimensions from the proximal end to the distal end. In yet anotherexample, a bus bar may have a material composition that varieslengthwise to increase electrical resistivity between proximal anddistal ends.

FIGS. 4D and 4E depict EC lites, 425 and 435 respectively, each having amonolithic EC device on a transparent substrate and a pair of bus bars.The width of each of the bus bars varies along its length. Thisgeometric lengthwise variation in the bus bars may produce a tintgradient zone (gradient in lengthwise direction) on the monolithic ECdevice when energized.

FIG. 4D depicts an EC lite, 425, including bus bars 430. Each of the busbars 430 has a varying width along its length that linearly taperslengthwise. In certain embodiments, the variation in width between thetwo ends may be between about 10% and about 100% from the average widthover the length of the bus bar. In one embodiment, the variation inwidth may be between about 10% and about 80% from the average width overthe length of the bus bar. In another embodiment, the variation in widthmay be between about 25% and about 75% from the average width over thelength of the bus bar. In this example, not drawn to scale, the bus bars430 are widest at the top of EC lite 425 and linearly taper lengthwiseto their thinnest width near the bottom of lite 425. Because of thevarying width, bus bars 430, when energized, establish a voltagegradient. For example, when energized, bus bars 430 have their highesteffective voltage at the top, and their lowest voltage at their bottomportion; a voltage gradient is established along the bus bars. Asdepicted in the right portion of FIG. 4D, a corresponding tintinggradient is established by virtue of the voltage gradient. Thus a tintgradient zone is established. Bus bars of varying width can be used inone or more zones of an EC lite having two or more zones as describedherein. In this illustrated example, a single tint gradient zone isestablished across an EC lite. Although a linearly tapered width isillustrated in FIG. 4D, a non-linearly tapered width can be used inother cases.

In certain embodiments, the tapering of the bus bars need not be asmooth taper. For example, a bus bar may have a stepped down width alongits length (i.e. stepwise width variation along its length). FIG. 4Edepicts an EC lite, 435, having a monolithic EC device and bus bars thathave stepped widths along their lengths. Each bus bar has three segmentswith stepped down widths along its length. Each bus bar has a firstwidth that spans a first portion, 440, of the length of the bus bar.Adjacent to the first portion, is a second portion, 445, of the lengthof each bus bar. The second portion has a second width shorter than thefirst width. Finally, adjacent to the second portion and having a thirdwidth, is a third portion, 450 of each bus bar. The net tinting gradienteffect may be the same as or similar to the smooth linearly taper busbars described in relation to FIG. 4D. One of ordinary skill in the artwould appreciate that varying the width of the bus bars can be done inother patterns, such as thicker in the middle than at the ends, etc.without escaping the scope of embodiments described herein, that is foran EC lite having bus bars of varying widths configured to create one ormore tint gradient zones on a monolithic EC device.

In one embodiment, an IGU includes two EC lites, each EC lite having atint gradient zone as described in relation to FIGS. 4D and 4E. In oneembodiment, the tint gradient zone of each EC lite is configured inopposition to each other, that is, one EC lite has a tinting front thatstarts at the opposite side (e.g., edge) of where the tinting front ofthe other EC lite starts. In this embodiment, a unique curtaining effectis established where the tinting fronts approach each other fromopposite sides and cross paths in the middle of the IGU. In one case,when transition is complete in both EC lites, the IGU may have a“privacy glass” tint level, of e.g. <1% T. In another embodiment, eachEC lite may be tinted independently to provide a “top down” tintgradient or “bottom up” tint gradient. In one embodiment, the tintgradient zones of the EC lites are registered together i.e. aligned sothat the tinting fronts of the EC lites start on the same side of theIGU and end at the other opposing side. In this latter embodiment,tinting of the IGU may be done for different tint levels with one lite,e.g., to provide a top down tint gradient of one intensity (absorptiongradient e.g.) for one tint level, and another (darker) tint level oftinting gradient when both lites are tinted. Either of the twoaforementioned IGU embodiments may have their individual EC lites tintedtogether or alternatively tinted asynchronously for yet another shadingeffect that is not possible with conventional monolithic EC devices.

In one embodiment, a bus bar may include an inner portion ofelectrically conductive material with a cross-sectional dimension (e.g.,width) that varies lengthwise, and an outer portion of electricallyresistive material. The outer portion may have geometry which isdesigned to couple and form with the inner portion a uniformcross-section along the length of the bus bar.

In certain embodiments, such as some embodiments described above, anelectrochromic window lite includes a monolithic EC device on atransparent substrate, wherein the EC lite includes at least one pair ofbus bars configured to produce a tint gradient zone on the monolithic ECdevice when energized. In some embodiments, tinting gradients areestablished using bus bars, where each bus bar has at least two portionsthat are highly conductive. The at least two portions are separated by aportion that is more resistive than the highly conductive at least twoportions, while still being electrically conductive. The more resistiveportion is configured adjacent to or overlapping the at least two highlyconductive portions. In this embodiment, the at least two highlyconductive portions are separated, they do not touch, but rather eachonly touches, and is in electrical communication with the more resistiveportion in between them. An electrical power source is configured topower only one portion of the at least two highly conductive portions ofeach of the at least one pair of bus bars. Each of the only one portionof the at least two highly conductive portions is proximate the sameside of the monolithic EC device as the other of the only one portion.One of these embodiments is described in more detail in relation to FIG.4F.

Tint gradient zones can also be created using bus bars having varyingmaterial composition along their lengths. For example, FIG. 4F depictsan EC lite, 455, having two bus bars, each configured along opposingedges (e.g., vertically, horizontally, etc.) and parallel to each otheron lite 455. In this example, each bus bar has highly electricallyconductive portions, 460 a, 460 b, and 460 c (collectively, 460), andless electrically conductive portions, 465 a and 465 b (collectively,465). In the illustrated example, less electrically conductive portions,465 a is between highly electrically conductive portions 460 a and 460b, and less electrically conductive portions, 465 b is between highlyelectrically conductive portions 460 b and 460 c. The less electricallyconductive portions, 465 a and 465 b, may be portions of a monolithicbus bar where the conductivity has been reduced by, e.g. changing themorphology of the bus bar material and/or perforating the material, etc.As an example, highly electrically conductive portions 460 a, 460 b, and460 c may be conventional silver based conductive bus bar ink, whileportions 465 a and 465 b may be a less conductive ink. In thisillustrated example, the bus bars may be connected to an electricalsource at the top portion, 460 a, of each bus bar. A voltage gradientmay be established along the length of the bus bars by virtue of theresistive portions 465 a and 465 b. That is, the top highly conductiveportions 460 a may have the highest voltage, and the middle highlyconductive portions 460 b may have a somewhat lower voltage because themore resistive portions 465 a lie between them preventing some of theelectrical current from flowing to the middle portions 460 b fromportions 460 a. Likewise the bottom-most highly conductive portions 460c may have the lowest voltage because the more resistive portions 465 blie between them and the middle highly conductive portions 460 bpreventing some of the electrical current from flowing from middleportion 460 b to lower portion 460 c. The net effect may be a tintgradient zone, for example, the one depicted in FIG. 4F. Highlyelectrically conductive portions 460 may be of the same or differentconductive material, and likewise, less electrically conductive portions465 may be comprised of the same or different conductive material. Thekey is that portions 465 are less electrically conductive than theiradjacent neighbors 460. Using this technology, a wide variety of voltageand/or resistance patterns may be established in order to createcorresponding tint gradient zones in an EC lite. In addition, acombination of bus bars of lengthwise varying width and those bus barsconfigured as described in relation to Figure 4F may be used. Forexample, each as partners in a bus bar pair and/or in individual tintgradient zones on an EC lite.

In certain embodiments, an EC lite may be configured to have acombination of tint gradient zones and tint zones that do not have tintgradient capability (non-gradient tint zones). One embodiment is amonolithic EC device having two or more tinting zones, where at leastone tinting zone is a tint gradient zone and at least one tinting zoneis a non-gradient tint zone. One embodiment is a monolithic EC devicehaving two or more tint gradient zones, with or without also having anon-gradient tint zone.

In one embodiment, the bus bars described in relation to FIG. 4F areconfigured such that each highly electrically conductive portion, 460 a,460 b, and 460 c, has its own electrical connection to a power source.Analogous to the separate bus bar pairs described in relation to FIG. 4A(or FIGS. 3A or 3D), the bus bars described in relation to FIG. 4F, whenconfigured with each highly electrically conductive portion 460 havingits own power source, may be used to create tint gradient zones withtinting patterns similar to those described in relation to FIGS. 4B and4C.

In certain embodiments that use powering mechanisms alone to createtinting zones, the tinting front may not be a clean line, but ratherhave a diffuse appearance along the tinting front due to the chargebleeding off into the EC device's adjacent zone which is not powered atthe time. In certain embodiments, resistive zones may be used to aid inmaintaining more well-defined tinting fronts. Resistive zones aredescribed in more detail below.

Resistive Zones with or without Configuring Powering Mechanism of ECDevices

In certain embodiments, resistive zones are configured in the monolithicEC device. These resistive zones may allow for more uniform tintingfronts, e.g., when used in combination with bus bar powering mechanismsdescribed herein. Referring to FIG. 5A, an EC lite, 500, much like EClite 200 of FIG. 2A, is configured with two pairs of bus bars forcreating two tinting zones, in this example (as depicted) a top and abottom zone. EC lite 500 may be incorporated into an IGU, 510, with aspacer 110 and a mate lite 115 as depicted. A major difference betweenlite 200 of FIG. 2A and lite 500 of FIG. 5A is that lite 500 does nothave a laser scribe 225 across the lite to bifurcate the EC device intotwo devices. Lite 500 has a single EC device over the viewable area ofthe lite. However, the EC device on lite 500 includes a resistive zone,505, that spans the width of the EC device. The heavy dotted line inFIG. 5A indicates the approximate position of resistive zone 505. Asdepicted in the IGU construct 510, resistive zone 505, like laser scribe225, may not be visible to the naked eye when the EC lite's zones arenot tinted. However, unlike laser scribe 225, when adjacent tintingzones of EC lite are tinted, resistive zone 505 may not be visuallydiscernible to the naked eye. This is illustrated schematically in theright portion of FIG. 5B. The reason resistive zone 505 tints is becauseit is not a physical bifurcation of the EC device into two devices, butrather a physical modification of the single EC device and/or itsassociated transparent conductors within a resistive zone. The resistivezone is an area of the EC device where the activity of the device,specifically the electrical resistivity and/or resistance to ionmovement is greater than for the remainder of the EC device. Thus one orboth of the transparent conductors may be modified to have increasedelectrical resistivity in the resistive zone, and/or the EC device stackmay be modified so that ion movement is slower in the resistive zonerelative to the EC device stack in the adjacent tinting zones. The ECdevice still functions, tints and bleaches, in this resistive zone, butat a slower rate and/or with less intensity of tint than the remainingportions of the EC device. For example, the resistive zone may tint asfully as the remainder of EC device in the adjacent tinting zones, butthe resistive zone tints more slowly than the adjacent tinting zones. Inanother example, the resistive zone may tint less fully than theadjacent tinting zones, and at a slower rate.

FIG. 5C is a perspective and a cross section, X-X, of EC lite 500 asdescribed with respect to FIGS. 5A and 5B. The cross section, X-X, spansthe upper and lower tinting zones (tinting zones 1 and 2, respectively)of EC lite 500 as well as resistive zone 505 (only the bus bars on thetop TCO are depicted in cross section X-X, they are orthogonal toresistive zone 505 in this example). Cross section X-X (lower portion ofFIG. 5C) is not to scale, but rather a schematic representation of thestructure of EC lite 500. On the glass substrate is an EC deviceincluding a first transparent conducting oxide layer, TCO 1, a secondtransparent conductive oxide layer, TCO 2, and sandwiched in between theTCOs is an EC stack which contains one or more electrochromic materials,e.g., the transitions of which are driven byintercalation/de-intercalation of ions, such as lithium ions. Resistivezone 505 is an area in the EC device where one or more layers of the ECdevice have their function impaired, either partially or completely, butdevice function is not cut off across the zone. For example, one or bothof the TCOs has a higher resistance to electrical flow in resistive zone505 than in the tinting zones. Thus, e.g., if tinting zone 1 isactivated, electrons flow across the TCOs at a given rate, but that flowis restricted along resistive zone 505. This allows the electrons to besufficiently retained in tinting zone 1 and thus leak more slowly acrossresistive zone 505 than otherwise would be the case if TCO function hadnot been impaired there. Resistive zone 505 could be thought of as a“dam” for electrical flow, impairing rate of electrical flow across it,the flow can be partially or fully impaired in one or both TCOs, forexample. Due to the restricted or slowed rate of electrical flow acrossresistive zone 505, ion intercalation in the EC stack between the TCOsat resistive zone 505 is also impaired. Because the EC device is notphysically cut into two devices, this is unlike conventional deviceshaving zones created by physical bifurcation of a single device.Resistive zone 505 may also have physical impairment of ion flow in oneor more of the EC material layers as well. In one example, both the topand bottom TCO's electrical conductivity is impaired, either partiallyor fully, in resistive zone 505, but the function of the EC device stacklayers is substantially unchanged. Thus, when one tinting zone is tintedand the adjacent zone is not-tinted, the device will tint underresistive zone 505. When adjacent tinting zones are both tinted, thereis no bright line discernible to the end user, because the device tintsunder resistive zone 505.

Resistive zone 505 may be fabricated, for example, by exposure of thearea at the resistive zone 505 to irradiation, e.g. laser or heatsource, in order to modify but not destroy the function at resistivezone 505. For example, one or both of the TCO layers may be heatedsufficiently to change the morphology while retaining the function,albeit impaired relative to the remainder of the TCO layers in thetinting zones. In certain embodiments, it is advantageous to impair thefunction of only one TCO in a resistive zone. Resistive zones may alsobe created by impairing the function of one or more layers of the ECdevice (or one or both TCOs) by chemical doping. For example, in oneembodiment the lower TCO is treated along a line (at resistive zone 505,e.g.) with heat and oxygen to create a more resistive TCO at theresistive zone. In another embodiment, one or both TCOs are fabricatedthinner along the resistive zone than the rest of the TCOs, e.g. TCOmaterial may be removed, but not cut through, along the resistive zone.

In certain embodiments, the resistive zones may be narrow, e.g. betweenabout 1 μm and 1000 μm wide, or may be wider, e.g. between about 1 mmand about 10 mm wide. Because the EC materials in resistive zones tintand do not necessarily leave a bright line contrast effect typical ofconventional laser isolation scribes, there is less concern as to thewidth of the described resistive zones. Thus, in other embodiments, aresistive zone may be, for example, wider than 1 mm, wider than 10 mm,wider than 15 mm, etc.

In the embodiment described in relation to FIGS. 5A, 5B, and 5C, each ofthe tinting zones has its own pair of bus bars. Thus tinting zones canbe colored independently by virtue of operation or the respective busbar pairs at each tinting zone. In other embodiments, multiple tintingzones may be configured between a single set of bus bars (e.g., two ormore bus bars located on opposing edges).

FIG. 5D depicts a perspective (top portion) and a cross section Y-Y(bottom portion) of an EC lite, 510, having two tinting zones ofvariable tinting level by virtue of a resistive zone, 515. In thisillustrated example, a single set of three bus bars, 525(a), 525(b), and520, is used with two tinting zones. Cross section, Y-Y, of EC lite 510spans left and right tinting zones (tinting zones 1 and 2, respectively)of lite 510 as well as resistive zone 515. Resistive zone 515 runsparallel to and between (approximately in the middle of EC lite 510) busbars 520 and 525(a) and bus bar 525(b) (from top to bottom as depictedin the perspective at the top of FIG. 5D). Cross section Y-Y (lowerportion of FIG. 5D) is not to scale, but rather is a schematicrepresentation of the structure of EC lite 510. On the glass substrateis an EC device including a first transparent conducting oxide layer,TCO 1, a second transparent conductive oxide layer, TCO 2, andsandwiched in between TCO 1 and TCO 2 is an EC stack which contains oneor more electrochromic materials, e.g., the transitions of which aredriven by intercalation/de-intercalation of ions, such as lithium ions.In this example, resistive zone 515 is an area of TCO 2, where the TCOfunction is impaired but not eliminated. For example, TCO 2 may have itsfunction impaired along a line. FIG. 5E includes two graphs showingplots of the local voltage V_(TCL), in TCO 1 and TCO 2 of the EC lite,510, of FIG. 5D that drives transition. At the left, a graph shows acurve 526 of the local values of V_(TCL), in the TCO 1. At the right, agraph shows a curve 528 of the local values of V_(TCL) in the TCO 2. Inthis example, when the EC device is energized, the bottom TCO 1 has alocal voltage potential V_(TCL) across its span similar to that of atypical transparent conductor for an EC device. According to curve 526of V_(TCL), in TCO 1, the voltage increases slightly in the middle awayfrom where bus bars 525(a) and 525(b) are disposed on TCO 1 wherevoltage is applied due to the sheet resistance and current passingthrough TCO 1. The increase will be near bus bar 525(a) and bus bar 520because of the higher current in this area due to higher voltagepotential between bus bar 525(a) and bus bar 520. But TCO 2, by virtueof resistive zone 515, has a higher V_(TCL), in tinting zone 1 than intinting zone 2. According to curve 528 V_(TCL), in TCO 2, the slightvoltage drops between the left hand side where bus bar 520 is disposedon TCO 2 and the resistive zone due to sheet resistance and currentpassing through TCO 2. At the resistive zone 515, the voltage sharplydrops. The voltage slightly drops between the resistive zone 515 and theright hand side due to sheet resistance and current passing through TCO2. The value of V_(eff) at any location between the bus bars is thedifference in values of curves 130 and 125 at that position on thex-axis corresponding to the location of interest. The result is thattinting zone 1 has a higher V_(eff) than tinting zone 2 and thus tintingzone 1 colors more darkly than tinting zone 2. This is represented inFIG. 5F. Of course, the two tinting zones can be configured as upper andlower portions when installed in a building, and they need not be sideby side as depicted.

FIG. 5G depicts an EC lite, 530, configured with a resistive zonecreated by inhibiting the electrical conductivity of only one of thetransparent conducting oxides. The EC lite is much like the onedescribed in relation to FIG. 5E, but in this embodiment one of the TCOsis cut through along the resistive zone (cut 550), while the other TCOis left intact. The EC device stack is unchanged in the resistive zone,only the top TCO is cut. The EC lite 530 has two sets of bus bars, 535and 540. Bus bar set 535 powers the lower TCO 1, while bus bar set 540powers the top TCO 2. The lower portion of FIG. 5G shows cross sectionZ-Z. The EC device will still at least partially color along theresistive zone by virtue of one of the TCOs being fully intact,monolithic, along with the EC stack. While there is a narrow region ofthe opposite TCO 2 missing, there is sufficient voltage potentialestablished between the intact TCO 1 and the edge of the cut (opposing)TCO 2 along the resistive zone to allow coloration of the EC device inthe resistive zone, albeit more slowly than if both

TCOs were intact along the resistive zone. The resistive zone may colormore lightly when only one of the tinting zones is powered, while withboth tinting zones powered, the resistive zone may fully tint orapproximate full tinting. Each portion of TCO 2 can be poweredindependently of TCO 1. In this way, separate zones, tinting zone 1 andtinting zone 2, may, e.g., be tinted more effectively. Since there is acut through the TCO 2, if only one zone is powered, a tinting level ofV_(TCL) is only established in that tinting zone. The cut in TCO 2 aidsin establishing and maintaining a uniform tinting front. In thisexample, since the TCOs are a type of moisture barrier, EC lite 530 maybe incorporated into an IGU where the EC device is hermetically sealedwithin the volume of the IGU, and/or a top coat may be used tohermetically seal the device, with our without lamination to asubstrate. A top coat would fill the open trench cut through TCO 2.

In certain embodiments, it may be more desirable to cut the bottom TCO 1rather than the top TCO 2. FIG. 5H shows EC lite, 530 a, where the cut,550 a, is made only through the bottom TCO 1. In this example, the topTCO 2 may maintain its hermeticity by virtue of an intact toptransparent conductor layer. The EC material may fill in the trench madeby cut 550 a, and thus tint along with the trench in TCO 1 that itfills, providing an area of inhibited coloration rate such as aresistive zone.

In certain embodiments, it may more desirable to cut the top TCO 2rather than the bottom TCO 1. FIG. 5G shows EC lite, 530, where the cut,550, is made only through the top TCO 2. An advantage of this embodimentmay be that the cut can be made after the EC device is fabricated, forexample, by laser processing performed after sputter coating.

The busbars 535 and 540 depicted in FIGS. 5G and 5H need not beparallel, e.g. the bus bars powering each TCO can be orthogonal to eachother. Also, the single monolithic TCO need not have two bus bars, butit is desirable so as to have more control over tinting of theindividual tinting zones. Bleaching function would work the same way butin reverse polarity to bleach the tinting zones. In the embodimentsdescribed in relation to FIGS. 5D-5H, the bus bars are configuredparallel to the resistive zone; in FIGS. 5I and 5J, like in FIG. 5C,e.g., the bus bars are configured orthogonally to the resistive zone.

In certain embodiments, there are no bus bars in the viewable area ofthe EC device, that is, in the area within the spacer of the IGU.Certain conventional EC technologies rely on bus bars running throughthe viewable area because of slow switching kinetics that wouldotherwise occur and/or due to ion conductor layer leakage currents thatdo not allow the EC device to switch across the entire viewable area oflarger IGUs (e.g. about a meter wide or more where bus bars wouldotherwise be configured outside the viewable area at the edges of thiswidth) without such bus bars in the viewable area to provide the extravoltage needed to compensate for the leakage current. Certainembodiments described herein, e.g. where cuts are made through one ofthe TCOs but not the EC device stack itself, do not require bus bars inthe viewable area because they include EC devices with very low leakagecurrent. Examples of such devices are described in U.S. patent Ser. No.12/814,279, filed Jun. 11, 2010, which is herein incorporated byreference in its entirety. For example, the embodiments described wherethe resistive zone includes a cut through one of the TCOs includeexamples where there are no bus bars in the viewable area of the ECdevice.

FIG. 5I depicts an EC lite, 555, configured with a resistive zone, 570,created by inhibiting the electrical conductivity across one of thetransparent conducting oxides, in this example a cut is made through theTCO nearer the substrate. The EC lite is much like the one described inrelation to FIG. 5C, but in this embodiment one of the TCOs is cutthrough along the resistive zone (cut 570), while the other TCO is leftintact. The EC device stack is unchanged in the resistive zone area,only the bottom TCO is cut. The EC lite 555 has two sets of bus bars,560 and 565. Bus bar set 560 powers both the upper and the lower TCOs intint zone 1 (TCO 1 and TCO 2), while bus bar set 565 powers tint zone 2.The lower portion of FIG. 5I shows cross section V-V (only the bus barson TCO 2 are depicted). The EC device will still at least partiallycolor along the resistive zone by virtue of one of the TCOs being fullyintact, monolithic, along with the EC stack. While there is a narrowregion of the opposite TCO 1 missing, there is sufficient voltagepotential established between the intact TCO 2 and the edge of the cut(opposing) TCO 1 along the resistive zone to allow coloration of the ECdevice in the resistive zone, albeit more slowly than if both TCOs wereintact along the resistive zone. The resistive zone may color morelightly when only one of the tinting zones is powered, while with bothtinting zones powered, the resistive zone may fully tint or approximatefull tint. Each portion of TCO 1 can be powered independently of TCO 2.In this way, separate zones, tinting zone 1 and tinting zone 2, may,e.g., be tinted more effectively. Since there is a cut through the TCO1, if only one zone is powered, a tinting level V_(TCL) is onlyestablished in that tinting zone. The cut in TCO 1 aids in establishingand maintaining a uniform tinting front. In this example, since the TCOsare a type of moisture barrier, EC lite 555 may be incorporated into anIGU where the EC device is hermetically sealed within the volume of theIGU, and a top coat may not be necessary because TCO 2 remains intact,although in one embodiment a top coat is applied to TCO 2. Because thebus bars in EC lite 555 are orthogonal to the resistive zone 570, thetinting front is also orthogonal to the bus bars.

FIG. 5J depicts an EC lite, 555 a, configured with a resistive zone, 570a, created by inhibiting the electrical conductivity across one of thetransparent conducting oxides, in this example a cut is made through theTCO distal the substrate. The EC lite is much like the one described inrelation to FIG. 5I, but in this embodiment TCO 2 is cut through whileTCO 1 is left intact. The EC device stack is unchanged in the resistivezone area, only the top TCO is cut. The EC lite 555 a has two sets ofbus bars, 560 and 565. Bus bar set 560 powers both the upper and thelower TCOs in tint zone 1 (TCO 1 and TCO 2), while bus bar set 565powers tint zone 2. The lower portion of FIG. 5J shows cross section T-T(only the bus bars on TCO 2 are depicted). The EC device will still atleast partially color along the resistive zone by virtue of one of theTCOs being fully intact, monolithic, along with the EC stack. Whilethere is a narrow region of the opposite TCO 2 missing, there issufficient voltage potential established between the intact TCO 1 andthe edge of the cut (opposing) TCO 2 along the resistive zone to allowcoloration of the EC device in the resistive zone, albeit more slowlythan if both TCOs were intact along the resistive zone. The resistivezone may color more lightly when only one of the tinting zones ispowered, while with both tinting zones powered, the resistive zone mayfully tint or approximate full tinting. Each portion of TCO 2 can bepowered independently of TCO 1. In this way, separate zones, tintingzone 1 and tinting zone 2, may, e.g., be tinted more effectively. Sincethere is a cut through the TCO 2, if only one zone is powered, a tintinglevel of V_(TCL), is only established in that tinting zone. The cut inTCO 2 aids in establishing and maintaining a uniform tinting front. Inthis example, since the TCOs are a type of moisture barrier, EC lite 555a may be incorporated into an IGU where the EC device is hermeticallysealed within the volume of the IGU, and a top coat may be necessarybecause TCO 2 is cut through, in one embodiment a top coat is applied toTCO 2. Because the bus bars in EC lite 555 a are orthogonal to theresistive zone 570 a, the tinting front is also orthogonal to the busbars.

When two bus bars ends of opposite polarity are located proximate eachother on an intact TCO, hot spots can result. Hot spots are described inU.S. patent application Ser. No. 13/452,032, filed Apr. 20, 2012 whichis incorporated by reference herein in its entirety. When using TCOsthat are cut through, e.g. as depicted in FIG. 5J, hot spots may beavoided because the proximate bus bars of a TCO layer cannotelectrically communicate with each other through the TCO. However, toavoid stress on the underlying EC device in the area along the resistivezone formed by cutting through TCO, the ends of the bus bars may beconfigured so they are not directly over (aligned with) the cut made forthe resistive zone.

One embodiment is an EC lite as described herein, where a resistive zoneis formed by partially cutting through one or both of the TCOs. Forexample, in one embodiment, e.g. analogous the embodiment described inrelation to FIG. 5J, the top TCO is only cut part way through, ratherthan cut through. In this way a resistive zone is established and thehermiticity of the EC device, imparted by the top TCO is left at leastpartially intact. FIG. 5K depicts another example.

FIG. 5K depicts an EC lite, 575, configured with two resistive zones,580 a and 580 b, created by inhibiting the electrical conductivityacross one of the transparent conducting oxides. In this example,partial cuts are made through the TCO distal the substrate (TCO 2). TheEC lite is much like the one described in relation to FIG. 5J, but inthis embodiment TCO 2 is not cut through, but only some TCO material isremoved to form resistive zones 580 a and 580 b. For example, laserablation is used to remove material only down to a fraction of the depthof the ITO. In one embodiment, between about 10% and about 90% of theTCO material is removed along the zone, in another embodiment betweenabout 25% and about 75% of the TCO material is removed, in yet anotherembodiment between about 40% and about 60% of the material is removed.By removing only part of the TCO material, a resistive zone isfabricated while not exposing the EC stack to the ambient. Lite 575 hasthree tint zones, by virtue of having two resistive zones. The EC lite575 has three sets of bus bars, 560, 565 and 566. Bus bar set 560 powersboth the upper and the lower TCOs in tint zone 1 (TCO 1 and TCO 2), busbar set 565 powers tint zone 2, and bus bar set 566 powers tint zone 3.Each tint zone can be independently controlled via powering the bottomTCO, and independently charging the TCO 2 bus bars, depending upon whichzone tinting is desired. Because the resistive zones have a higher sheetresistance relative to the bulk TCO, charge loss over this barrier isslow and allows the powered zone to fully tint while the tinting frontapproximates the position of the resistive zone.

The lower portion of FIG. 5K shows cross section S-S (only the bus barson TCO 2 are depicted). The EC device will still at least partiallycolor along the resistive zone by virtue of TCO 2 being fully intact,monolithic, along with the EC stack. The resistive zone may color morelightly when only one of the tinting zones is powered, or not at all,depending on its width and the thickness of the TCO in the resistivezone. With adjacent tinting zones powered, the resistive zone may fullytint or approximate full tinting. In this example, since the TCOs are atype of moisture barrier, EC lite 575 may be incorporated into an IGUwhere the EC device is hermetically sealed within the volume of the IGU,and a top coat may be necessary because TCO 2 is at least partially cutthrough, in one embodiment a top coat is applied to TCO 2. Because thebus bars in EC lite 575 are orthogonal to the resistive zones 580 a and580 b, the tinting front is also orthogonal to the bus bars andapproximates the line defined by the resistive zones.

Note, in FIG. 5K, the bus bars ends are substantially coextant with theresistive zones. In one embodiment, bus bar material is applied and thenthe resistive zones are formed by cutting through the bus bar materialand at least some of the top TCO. In certain embodiments the top TCO iscut through, while not cutting the EC device stack through (a portion ofthe EC stack may be cut, but sometimes not through the IC material so asnot to form electrical shorts along the resistive zone). By applying,e.g., only two lines of bus bar material (e.g. silver based ink) andfiring the bus bars, the resistive zones and individual bus bar pairscan be fabricated in the same process by cutting through the bus barmaterial and into or through the top TCO simultaneously. This savesprocess steps. The bus bar on the bottom TCO 1 is cut through withoutcutting through the bottom TCO. In one embodiment the bus bars on thetop TCO are formed by cutting through along with the top TCO, eitherfully or partially cut, while the bottom bus bars are applied separatelyto each tinting zone. In certain embodiments, each tinting zone's busbars are applied individually to each tinting zone. The latter may bedone to avoid the aforementioned hot spots, e.g. when cutting throughthe bus bar and TCO in the same process, the ends of the newly formedbus bars are necessarily aligned with the cut in the TCO, since theywere from the same cutting process.

Certain embodiments concern methods of fabricating apparatus and devicesdescribed herein. One embodiment is a method of forming an EC litehaving two or more tinting zones, the method including a) forming a ECdevice (e.g., a monolithic EC device), b) applying a single bus bar tothe top TCO of the monolithic EC device, and c) cutting through the busbar and at least part way through the top TCO thereby fabricating saidtwo or more tinting zones each having separate bus bars on the top TCOby virtue of c.

Resistive zones need not be linear as depicted, but rather may be of anyshape. For example, for desired effects, one might choose a resistivezone that is zigzagged, curved or irregularly shaped along adjacenttinting zones.

In certain embodiments, resistive zones are used to define a perimeter,closed or open, of a region of an EC window. For example, theseresistive zones can be used to highlight particular symbols or shapes inthe viewable region of the EC window. One embodiment with such aresistive zone is illustrated in FIGS. 6A and 6B. For example, an enduser may wish to have an area of the EC window that does not tint, orthat becomes tinted more slowly, than the remainder of the tintable ECwindow.

FIG. 6A depicts an EC lite, 600, which includes a single pair of busbars, 105, as well as a resistive zone, 605. In this example, theresistive zone is in the shape of a closed rectangle (as indicated bythe dotted line). Resistive zone 605 may not be visually discernible tothe naked eye. In one embodiment, resistive zone 605 is configured suchthat the portions of the TCOs of the EC device in the resistive zone (asindicated by the dotted line) have a higher electrical resistance thanthe portions of the TCOs in the remainder of the EC device on eitherside of the resistive zone (in this example both outside and inside therectangular perimeter zone), but the resistive zone still passes charge.In this embodiment, when the EC device is tinted, the area around theresistive zone 605 tints first, the tinting front slowing when itreaches the rectangular closed resistive zone 605. This momentarily,e.g. for a period of minutes, gives the effect of a small untinted viewport in a larger tinted window. As the charge bleeds beyond theresistive zone and into the untinted rectangular region within the zone,this gives the effect of the small untinted view port closing as ittints. In another embodiment, resistive zone 605 is configured such thatthe portions of the TCOs of the EC device in the resistive zone (asindicated by the dotted line) have a very high resistance to electricalcharge as compared to the portions of the TCOs in the remainder of theEC device on either side of the resistive zone (in this example bothoutside and inside the rectangular perimeter zone), that is, theresistive zone effectively blocks electrical charge. In this embodiment,when the area outside the zone is tinted, the area inside the zone maynever tint because the charge may not be able to pass the resistivebarrier 605. This gives the effect of a small untinted view port in alarger tinted window, so long as the EC device is tinted. In anotherembodiment, resistive zone 605 is configured such that the portions ofthe TCOs of the EC device in the resistive zone (as indicated by thedotted line) and in the region within the resistive zone have a veryhigh resistance to electrical charge as compared to the portions of theTCOs in the remainder of the EC device on the outside of the resistivezone.

FIG. 6B shows a similar EC lite, 610, having a resistive zone, 615,which is “open” by virtue of a gap, 620, in the perimeter. In thisexample, the resistive zone 615 is configured to block electricalcharge. When the EC device is tinted, the area around the resistive zone615 tints first, the tinting front slowing when it reaches therectangular closed resistive zone 615, except at the open portion 620,where the tinting front gives the effect of “pouring in” or “filling in”(as indicated by the two dotted arrows) the rectangular region withinresistive zone 615. Eventually, when the area inside resistive zone 615is tinted, resistive zone 615 may no longer be discernible to the nakedeye, as the EC device colors under the zone, as described above.Configuring resistive zones in such a way can be used to achievepermanent or transient tinting effects on EC windows, e.g., to display alogo or words in a transient manner for presentation during marketingpurposes, or to achieve tinted and non-tinting zones on an EC lite. EClites so configured can be incorporated into IGUs as describe and/orlaminated with mate lites.

One of ordinary skill in the art, armed with this disclosure, wouldappreciate that tint gradient zones can be used with resistive zones andthis combination is within the scope of the embodiments describedherein.

Although the foregoing embodiments have been described in some detail tofacilitate understanding, the described embodiments are to be consideredillustrative and not limiting. It will be apparent to one of ordinaryskill in the art that certain changes and modifications can be practicedwithin the scope of the above description and the appended claims.

1. An electrochromic (EC) window comprising: an EC device on atransparent substrate, the EC device comprising bus bars; a region ofthe transparent substrate that is not covered by the EC device, theregion capable of providing, when not mitigated, a bright spot or brightregion when the EC device is tinted; and an obscuring material over theregion, wherein the obscuring material has a lower transmittance thanthe transparent substrate.
 2. The electrochromic window of claim 1,wherein the region is a pinhole, a scribe line, or an edge line.
 3. Amethod of obscuring a bright area produced by a region of a transparentsubstrate that is not covered by an EC device, the method comprising: i.providing an electrochromic lite having the EC device on a substrate;ii. identifying a site of the bright area on the substrate; and iii.applying an obscuring material over the site, wherein the obscuringmaterial has a lower transmittance than the substrate.
 4. The method ofclaim 3, wherein the region is a pinhole, a scribe line, or an edgeline.
 5. An electrochromic window comprising: an EC device disposed on atransparent substrate, the EC device comprising a first transparentconducting oxide (TCO) and a second TCO; and a pair of bus bars coupledto the first and second TCOs, wherein each bus bar is configured togenerate and maintain a voltage drop along the bus bar's length whenvoltage is applied, so that the electrochromic window maintains a tintgradient along its length.
 6. The electrochromic window of claim 5,wherein the voltage drop is achieved by varying thickness or width alongthe length of each of the pair of bus bars.
 7. The electrochromic windowof claim 5, wherein the voltage drop is achieved by varying compositionalong the length of each of the pair of bus bars.
 8. The electrochromicwindow of claim 5, wherein the voltage drop is achieved by varyingresistivity along the length of each of the pair of bus bars.
 9. Theelectrochromic window of claim 8, wherein each bus bar of the pair ofbus bars comprises two portions of an electrically conductive material,and an electrically resistive material establishing electricalcommunication between the two portions of the electrically conductivematerial, the electrically resistive material, although electricallyconductive, having less electrical conductivity than the electricallyconductive material.
 10. The electrochromic window of claim 9, whereinthe electrically conductive material is a silver based ink.
 11. Theelectrochromic window of claim 9, wherein the electrically resistivematerial is a silver based ink.
 12. The electrochromic window of claim5, wherein the voltage drop is achieved by varying cross-sectional areaalong the length of each of the pair of bus bars.
 13. The electrochromicwindow of claim 5, wherein the voltage drop is achieved by varyingmorphology along the length of each of the pair of bus bars.
 14. Theelectrochromic window of claim 5, wherein voltage is applied at one orboth ends of each of the pair of bus bars.
 15. The electrochromic windowof claim 5, wherein voltage is applied at more than one point along atleast one of the pair of bus bars.
 16. The electrochromic window ofclaim 15, wherein each bus bar of the pair of bus bars comprises a pairof power leads.
 17. The electrochromic window of claim 16, wherein eachbus bar of the pair of bus bars is configured to be powered by a firstvoltage at one power lead and by a second voltage at the other powerlead.
 18. The electrochromic window of claim 5, wherein each bus bar ofthe pair of bus bars comprises a material having regions of higher andlower electrical conductivity, wherein the regions of lower electricalconductivity are areas where the material is perforated.